/*
 * jPOS Project [http://jpos.org]
 * Copyright (C) 2000-2015 Alejandro P. Revilla
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.jpos.security;

import org.bouncycastle.util.encoders.Base64;
import org.jpos.iso.ISOUtil;

import java.io.IOException;
import java.io.InputStream;

@SuppressWarnings("unused")
public class SystemSeed {
	public static byte[] getSeed(int l) {
		return getSeed(0, l);
	}

	public static byte[] getSeed(int offset, int l) {
		if (offset + l > seed.length)
			throw new IllegalArgumentException("Invalid offset/length");
		byte[] b = new byte[l];
		System.arraycopy(seed, offset, b, 0, l);
		return b;
	}

	private static final byte[] seed;

	static {
		try {
			byte[] _s0 = get("/META-INF/q2/.seed");
			byte[] _s1 = get("/META-INF/.seed");
			seed = _s1 == null ? _s0 : ISOUtil.xor(_s0, _s1);
			if (seed == null || seed.length < 16)
				throw new IllegalArgumentException("Invalid seed");
		} catch (IOException e) {
			throw new IllegalArgumentException("Invalid system configuration");
		}
	}

	private static byte[] get(String path) throws IOException {
		InputStream is = SystemSeed.class.getResourceAsStream(path);
		if (is != null) {
			try {
				byte[] b = new byte[is.available()];
				is.read(b);
				return Base64.decode(b);
			} finally {
				is.close();
			}
		}
		return null;
	}
}
